Electric heating system



Aug. 14, 1928.

L. P. HYNES ELECTRIC HEATING SYSTEM Filed Dec. 6, 1924 cow INVENTOR LEE P. HYNES ATTORNEY Patented Aug. 14, 1928.

UNITED STATES PATENT OFFICE.

LEE 2. EYNES, or ALBANY, NEW YORK, ASSIGNOR, BYMES E ASSIGNMENTS, T0 ooN- soLInA'rEn CAR-HEATING COMPANY, INCL, or ALBANY, NEW YORK, A CORPORA- 'TION OENEW "roux.

I ELECTRIC HEATING SYSTEM.

hPplicationfilerl December 6, .1924, Serial No.. 754333.

For .-a detailed description of the present form of my invention, reference may be had to the following specification and to the accompanying drawings forming a part thereof.

My invention relates to heating systems particularly designed for heating railway cars, but 'usable under any similar conditions.

' In systems of this type it viscustomary to employ a number of heaters in series to meet the conditions of high voltagesay 600 voltsand if an accidental ground occurs at any point along this series it brings excessive voltage on those heaters of the series lying between the said ground and the trolley. These are liable to be burned out by the abnormal current which results from such excessive voltage. 7

It is also customary 'in systems of this type to keep the temperature of the car at an approximately constant degree by means of a thermostat in the car which cuts off the heaters when the car temperature exceeds a predetermined degree and reconnects them when it falls below a predetermined" degree. This automatic system'has he'retofore'involved a complicated arrange ment of circuits and resistances which are required for protecting the small and delicate contacts of the thermostat.

7 By my present invention I provide a very simple and effective means for protecting the heaters from injury 'in the event of a groiuid, and the same apparatus also provides a muchsimplified means of automatic regulation of the. car temperature.

In the drawing H, H, etc., indicate a series of electric heaters distributed in the customary way throughout an electric railway car and of any of the customary forms; These heaters receive current directly from trolley A by a circuit which includes blow out magnet B and contacts C of a magnetically operated switch worked by a magnet D. Su ch switches are well known and need not be further described herein, "it being noted, however, that the :switch contacts C are closed by the energizing of magnet D and opened when it becomes deenergized. From contacts C the circuit goes through the four heaters H, H, etc, in series toground at G. It will be readily understood that if an accidental ground occurs at aLpoint on this heater circuit-say at the point .X--the current will then pass to ground at X, through the route of less resistance provided by the two heaters between X and the trolley rather than at G through the higher resistance route through all four heaters. As a result the trolley which contains only the two left-hand heat ers H, .H and so has but half the resistance of the normal heater circuit containing all four heaters. The efl'ect will be an abnormal current in the two left-hand heaters which remain .in circu t.

By my present device I provide at each heater H a small fuse K that will melt and open its circuit whenever the temperature of the heater exceeds a predetermined degree. This fuse is preferably mounted on the :outsi-de of the heater case where it may be readily renewed by .an authorized person in the event of its fusion. These fuses K, K, etc, are included in series in a shunt cir-. cui'twof high resistance which branches from the main heating circuit hereto-fore traced at .the point a on the trolley side. Thence it goes toahigh artificial resistance Rof about 5000 ohms, andthen through the severalflfuses K, K, etc, in series, .to a small at-use F that will melt at approximately one ampere. Thence it goes through the switch magnet D :to ground at G So long as this circuit isintact the current therein will flow in the coils of magnet ,D- which will thus hold closed the switch. contacts C that control the main heater circuit. above described. If, however, anyone of the heaters H, H, etc., becomes overheated by reason of any accidental ground, as heretofore explained, the corresponding fuse K will open the aforesaid emergency circuit through magnetD and thereby cause it to break the. main heater circuit at the switch contacts C and sozsave the heaters from injury. But I also voltage will .be applied to a heater circuit switch magnet D the current Which would otherwise go through it to ground at G It will be understood that the artificial-rasistance R, by reason of its magnitude com pletely dominates the current in the shunt circuit whether that circuit goes to ground through magnet D at G or through thermostat T at G Thus the thermostat will effectively short-circuit magnet D whenever it closes its contacts and will re-energize that" magnet whenever it opens its contacts. The current, which resistance R permits to flow in this emergency circuit,'is so small that the circuit can be protected by the small one-ampere fuse F aforesaid. It may also be observed that the fuses K, K, etc., do not actby virtue of the heating efiect of the current flowing through them, but by the heat coming to them externally from an over-heated and endangered heater. So it is the fuse F, that is dependent on the current it carries, which controls the shunt circuit independently of the fuses K, K, etc.,- although the latter are in the same circuit.

In operation current will vflow from thetrolley through resistance R and the fuses K, K, etc., in series, then through fuse F and magnet D to ground so long as the car is colder than the thermostat setting. Coil D Will be energized closing contacts C and putting current on the heaters H. For'this result it is only necessary to close the main heater switch. Thereafter when the car becomes heated to the predetermined degree thermostat T will make contact to ground G thereby short-circuiting magnet D and opening the heater switch contacts C. When the temperature falls again the heaters will be automatically turned on again as above described. It will be observed that the resistance R- reduces the current in the contacts of thermostat T to a minute amount which can be broken without injury or danger to these contacts.

' While a constant regulation of the car temperature is thus secured the same apparatus will also serve to open the heater circuit in the event of an accidental ground as above described. 7

By means of the arrangement I have described I accomplish two effects, each-of which have heretofore required its own separate organization. Moreover the said ar- The closure of this 'ther rangement is much simpler than either one of the said separate organizations and more reliable.

It is to be understood that the fuses K, K, etc, are typical of any local device brought into action by an abnormal degree otheat in the adjacent heaters and serving when it acts to cause switch contacts.

, .VVhat I claim as new and desire to secure by Letters Patent is: g

1. An electric heating system comprising an electric heater, a circuit-closing switch therefor, a magnet controlling said switch, a circuit for said 'magnet .shunting the heater with a device adjacent to' the heater and responsive to excessive heat therein which controls the saidfmagnet together with a thermostat responsive to 'the temperature of the apartment heated and also controlling the said magnet. V

2. An electric heatingsystem comprising a plurality of heaters in series, devices extrolling the' said switch, a magnet in said shunt circuit for operating the said switch and a thermostat responsive to thetemperature of the apartment heated controlling the said magnet." Y

the opening of the 4-. An electric heating'system comprising a circuit containing a heater and its controllingjswitch, and a shunt circuit containing resistance and a device responsive to an excess of heater temperature which controls said switch, the shunt circuit having branches containing respectively a magnet controlling the heater switch and athermostat responsive to the temperature of the a partment heated. v

An electric heating system comprising a heater and a switch for theheater circuit, anda shunt circuit containing in series a resistance anda circuit-opener adj acent to and responsive. to theheat of said heater and having two branches onecontaining a mag- 6. An electric heatingsystem comprising a.

respective heaters but external thereto actof heat in any heater and a shunt circuit 1 ing to open the circuit in response to an excontaining a resistance and controlling concess of heat in any heater. a tacts thermostatically operated, said contacts 7. An electric heating system comprising acting (0 open Said switch upon an excess :1 series of electric heaters and a lnagneticalof heat in the apartment heated. l y 0perated switch therefor, thermally re- Signed at Albany, county of Albany and 15 sponsive devices adjacent to the respective State of New York, this 22nd day of Novemheaters but external to the heater circuit actber, 1924. ing to open the said switch upon an excess E HYNES. 

